As an apparatus configured to collect various data from a monitoring target in a plant, Patent Document 1, for example, has proposed a data collection apparatus which collects binary data on control information outputted by a control apparatus to an iron and steel plant; collects binary data on event information on the iron and steel plant to be controlled by use of the control information outputted by the control apparatus; adds a common key to the binary data on the control information and the binary data on the event information which are collected at the same time; and accumulates the binary data on the control information with the added common key while accumulating the binary data on the event information with the added common key.